The heat-generating moisture absorption property refers to a property by which dry fibers generate heat when absorbing moisture (water). For example, a futon that has been exposed to the sunlight during the daytime, and then has been taken into a room will have the same temperature as the room temperature after the passing of several hours. However, when such futon is brought into contact with human skin, the person feels that the futon is warm. This phenomenon is known to be attributed to the heat-generating moisture absorption property possessed by the fibers of the futon.
As conventional methods for producing a heat-generating, moisture-absorbing fiber, high moisture absorbing and desorbing fibers obtained by a hydrazine cross-linking treatment of an acrylic fiber, a hydrolysis treatment, and the conversion of a carboxyl group to a salt form, and production methods thereof have been proposed in Patent document 1 and Patent document 2.
However, these proposals relate to the modification of an acrylic fiber itself and, thus, were difficult to apply to other fibers.
The present inventors have already proposed methods in which a different material is graft polymerized to the surface of a fiber using radiation, thereby performing an antimicrobial treatment or the like (Patent document 3 and Patent document 4).
However, there has been room for a further improvement in obtaining a sliver and a spun yarn that are imparted with a deodorizing function and/or a heat-generating moisture absorption function, and a fiber product using them.